Fluid pumps are used extensively in many areas. In some areas, such as chemistry, medicine and biotechnology, relatively low fluid volumes and controlled flow rates are required. An example is the delivery of a pharmaceutical solution or suspension from a container to a delivery point. A number of piezoelectric pumps, including micro-pumps, have been developed. The amount of fluid pumped by a piezoelectric pump typically relates to the driving voltage and pulse width of the electrical signal used to energize the piezoelectric element. This provides an “open-loop” method for controlling the pump. The “open-loop” method does not provide sufficient accuracy for all applications.